Stroke is a cerebrovascular accident with high disability and mortality rates. One of the main factors affecting the independence of stroke survivors is hand function, which is closely related to daily activities, such as feeding and self-cleaning. Neuro-rehabilitation following a stroke or other cerebrovascular event is a major future challenge as populations age and have increasing longevity.
Electroencephalography (EEG) is a technique for measuring bioelectrical signals generated by the cerebral cortex of a brain. The signals are directly related to voluntary motor contributions from the central nervous system (e.g., EEG motor imagery, the thinking and planning of a physical task). EEG signals are more directly related to the voluntary contribution with stronger signals from a patient in the early post-stroke stage. Currently the types of EEG systems that can measure these signals are non-portable, that is, they are sufficiently large as to restrict their use to a research laboratory environment. The measurement system requires a lengthy period to prepare and correctly position all the EEG electrodes. Further, without visual indicators, correct electrode placement is difficult to verify and typically must be performed by skilled technicians.
Various devices have been used in an attempt to correctly position and hold EEG electrodes adjacent to a patient's scalp. For example, caps are used to position the EEG electrodes. Such electrode caps facilitate positioning of EEG electrodes by technicians within a short period of time (e.g., about 5 minutes). Following electrode positioning, conductive gel is injected to reduce the scalp-electrode impedance and thereby record strong EEG signals.
However, conventional attempts to position EEG electrodes using various headgear are insufficient because they do not appropriately account for variations among head sizes and shapes in the patient population. Typically, conventional approaches use several specific sizes in order to approximate various head sizes along with elastic materials to roughly elongate a cap to more closely fit different head shapes. However, conventional electrode caps are based on approximating the upper head as having a hemispherical shape. Since the human head does not have a hemispherical shape, an equal elongated head size approximation method causes error in the electrode positioning.
Thus there is a need in the art for an improved EEG electrode positioning device, particularly a positioning device that is lightweight with sufficient resilient properties to ensure proper electrode positioning on a variety of head sizes and shapes. There is a further need in the art for visual indication that the electrodes are correctly positioned and that the electrode-scalp impedance is within an acceptable range for EEG signal measurement. Such a device could facilitate a portable brain-training system with minimal set-up time that could be used in clinical and residential settings.